The Cytopathology Section provides complete diagnostic service in exfoliative cytology and fine needle aspiration cytology. The section also routinely applies immunocytochemistry techniques to confirm and/or enhance cytological diagnostic accuracy. In addition, the section collaborates in various clinical research projects utilizing routine microscopy as well as special staining techniques and immunocytochemistry. In conjunction with Dr. M.A. Stetler Stevenson in the Hematopathology Section, we are initiating flow cytometry as an ancillary diagnostic technique in bladder washings. The fine needle aspiration service is designed to afford maximal flexibility for clinicians and patients. Clinicians may request that: 1) a pathologist perform the aspiration; 2) a cytotechnologist assist the clinician in handling the specimen; 3) aspirations of deep lesions he performed by the radiologist with the assistance of a cytotechnologist to evaluate adequacy of the specimen. An example of one collaborative clinical research project involves clinical trials currently being conducted to study the use of the monoclonal antibody RFB4-RICIN A chain conjugate for refractory CD22 positive B-cell lymphoma. Our collaborative effort in this project involves the cytomorphologic evaluation of cytopathology specimens in order to: 1) document the presence of lymphoma and CD22 positivity prior to initiation of immunotoxin therapy and 2) monitor response by evaluating CD22 levels and presence of immunotoxin. Another collaborative project with the Whitman-Walker AIDS clinic is evaluating the prevalence of cervical premalignant lesions in mv infected women. A few reports in the literature have cited a high rate of dysplasias in HIv infected women. These findings, if substantiated, have implications for cervical screening recommendations for this population. Two previous projects have included evaluation of the comparative utility of core needle biopsy and fine needle aspiration in the diagnosis of soft tissue lesions, and the role of cytology in the diagnosis of Pneumocystis in HIV infected patients.